Random walks in random Dirichlet environment

Random walks in random Dirichlet environment (RWDE) plays a special role in random environment since the annealed law is the law of a reinforced edge oriented random walk. In these talks I will present several aspects of these processes: some first results in the multidimensionnel ballisitic case, and some little miracle in dimension one. Finally, I will present some strinking relations with hypergeometric integrals associated with arrangement of hyperplans.